/Engine/Source/Runtime/Engine/Public/InstancedStaticMeshDelegates.h
Delegate called when the tree of a HISM has been (re)built.
typedef TMulticastDelegate_TwoParams< void, [UHierarchicalInstancedStaticMeshComponent](API\Runtime\Engine\Components\UHierarchicalInstancedStaticMesh-) *, bool > FOnTreeBuilt